1. Field of the Invention
The present invention relates to a semiconductor device tester which gives a guarantee of reliability, and more specifically to a semiconductor device tester which is possible to make an acceleration reliability test by heating an integrated circuit to be tested (called a "test IC" in this specification).
2. Description of Related Art
A semiconductor device tester configured to individually test a semiconductor device is disclosed in Japanese Patent Application Laid-open Publication JP-A-2-052263.
A construction of this conventional semiconductor device tester is shown in FIG. 1. In the shown conventional semiconductor device tester, a test IC 102 includes a temperature sensor part 114 provided in addition to a function part 113 which is inherently required in an inside of the test IC 102. A controller 105 compares a temperature detected by the temperature sensor part 114 and outputted from a measuring part 104, with a predetermined target temperature. As the result, when the temperature detected by the temperature sensor part 114, which is a temperature in a testing apparatus 112, reaches the predetermined target temperature, a test of the test IC is begun by using a measuring device 115. When the temperature detected by the temperature sensor part 114 does not reach the predetermined target temperature, the controller 105 sends a control signal to an external heating-cooling device 103, so that the external heating-cooling device 103 heats or cools the tester 112 so as to make the temperature of the test IC 102 reach the predetermined target temperature.
As mentioned above, the conventional semiconductor device tester has been constructed to ensure the testing to be performed at a constant temperature by changing the temperature of the testing apparatus 112 by action of the external heating-cooling device 103.
However, the conventional semiconductor device tester shown in FIG. 1 is disadvantageous in that the temperature of the test IC 102 can be changed only by varying the temperature of the whole of the inner part of the testing apparatus 112 by action of the external heating-cooling device 103. When a plurality of semiconductor devices are tested together in the testing apparatus 112, even if the temperature of the testing apparatus 112 reaches the target temperature, all of the plurality of semiconductor devices are not necessarily at the same temperature, and therefore, all of the semiconductor devices cannot be tested at the same temperature.
In an accelerated reliability test of a plurality of semiconductor devices, since the acceleration coefficient depends upon an applied voltage and the temperature of the test ICs, the result of the acceleration reliability test is not reliable if the temperature of the test ICs are different from each other.